The following abbreviations are utilized herein:
ACK acknowledgement
AG access gateway
BE best effort
BS base station
CN correspondent node
HARQ hybrid automatic repeat-request
IEEE institute of electrical and electronics engineers
MN mobile node
NACK negative acknowledgement
QoS quality of service
RN relay node
rtPS realtime polling service
Wi-Fi WLAN based on the IEEE 802.11 standard
WiMAX worldwide interoperability for microwave access (IEEE 802.16 standard)
WLAN wireless local area network
WMN wireless mesh network
A mesh network is a network that employs one of two connection arrangements, full mesh topology or partial mesh topology. In the full mesh topology, each node is connected directly to each other node. In the partial mesh topology, nodes are connected to only some, not all, of the other nodes.
A WMN is a wireless network that handles many-to-many connections and is capable of dynamically updating and optimizing these connections. This may be (but does not have to be) a “mobile network” in which it is assumed that each (or at least some) of the nodes of the network are mobile units (e.g., MNs) that change position over time. The dynamic management of complex routing information, very likely to include information about external networks (e.g., the internet and gateways thereto), is arguably the biggest challenge for (dynamic) mesh protocols. WMNs may communicate in accordance with various communication standards such as Wi-Fi and WiMAX, as non-limiting examples.
Within a WMN, a system that has a direct connection to an IP backbone is termed a mesh BS or AG. Usually there is no direct link from MNs to an AG and traffic is routed through one or more hops over RNs. Therefore, the scheduling in WMNs should consider multi-hops. There are two conventional mechanisms to schedule data transmission in WMNs: centralized scheduling and distributed scheduling. In centralized scheduling, the AG or mesh BS collects the control and data packet information to determine the resource assignment for each node and ensures that transmissions are coordinated to ensure collision-free scheduling. When using distributed scheduling, each RN or mesh router performs independent scheduling while coordinating with their extended neighbors. Distributed scheduling is generally more flexible and efficient on data transmission in WMNs due to the distributed channel access control.